Plasma processing apparatus and method

ABSTRACT

There is provided a plasma processing apparatus including a plasma generating unit for generating a plasma in a processing chamber in which a set processing is performed on a substrate serving as an object to be processed. The plasma processing apparatus further includes a particle moving unit for electrostatically driving particles in a region above the substrate to be removed out of the region above the substrate in the processing chamber while the processing on the substrate is performed by using the plasma. In addition, there is provided a plasma processing method of a plasma processing apparatus including the steps of generating plasma in a processing chamber in which a set processing is performed on a substrate serving as an object to be processed; and performing the processing on the substrate by the plasma.

FIELD OF THE INVENTION

The present invention relates to a plasma processing apparatus andmethod; and, more particularly, a plasma processing apparatus and methodusing a processing chamber for performing a plasma processing on asubstrate.

BACKGROUND OF THE INVENTION

Recently, a treatment using a plasma (hereinafter, referred to as“plasma processing”) such as an etching, sputtering and CVD (chemicalvapor deposition) has been employed to be performed on an object to beprocessed such as a semiconductor wafer (hereinafter, referred to as“wafer”) in a manufacturing process of a semiconductor apparatus.

An apparatus for carrying out such process (shown in FIG. 8) has aprocessing chamber 800, which is a cylindrical container, for performinga plasma processing on a wafer. The processing chamber 800 includes achamber sidewall 810, an upper electrode 811 installed at the top of thechamber 800, a lower electrode 812 installed in a lower portion of theprocessing chamber 800, an ESC (electrostatic chuck) stage 820 and afocus ring 821 mounted on an upper side of the lower electrode 812, anda baffle plate 830 interposed between the chamber sidewall 810 and thelower electrode 812.

The upper electrode 811, which has a plurality of through holes notshown in the drawing, serves as a shower head for introducing a processgas for the plasma processing into the processing chamber 800 throughthe through holes. The lower electrode 812 is connected to a highfrequency power supply 813. The focus ring 821 is made of a ring-shapedmember formed to enclose a wafer mounted on the upper side of the ESCstage 820.

The ESC stage 820 includes an ESC electrode 820 a embedded in the ESCstage 820 to electrostatically adsorb the mounted wafer onto the ESCstage 820. The ESC electrode 820 a is connected to a variable powersupply 822 for providing electric power required to adsorb the waferonto the ESC electrode 820 a.

In the plasma processing apparatus shown in FIG. 8 is formed a plasmaregion of the plasma generated by a high frequency electric field formedin a space between the upper electrode 811 and the lower electrode 812as shown in the figure. The plasma processing apparatus performs anetching on, for example, an oxide film already formed on an upper sideof the wafer by the generated plasma. The particles detached from aninner wall of the chamber sidewall 810 by the etching float aroundinside the processing chamber 800. After the etching is completed, theparticles are removed by exhausting the processing chamber 800 through asmall through hole (not shown) located in the baffle plate 830 by usinga pump which is not shown.

Such particles are negatively charged by the electrons in the plasma tofloat around the plasma region above the wafer during the etchingprocess, and will be attached onto the upper side of the wafer tothereby contaminate the wafer after the plasma production is stopped bycompleting the etching process.

There are disclosed techniques that can be employed to prevent theparticles from being attached onto the upper side of the wafer asdescribed above, wherein the charged particles are actively removed byusing another electrode installed in the processing chamber 800 beforethe plasma generation or after the plasma extinction (for example,References 1 and 2).

(Reference 1) Japanese Patent Laid-open Application No. H10-284471

(Reference 2) European Patent Publication No. 1119030

However, although the particles can be driven from the region above thewafer towards the other electrode before the plasma being generated orafter the plasma being extinguished by the techniques described inReferences 1 and 2, it is not practical to remove the particles whilethe plasma is being produced because the other electrode causes togenerate an abnormal discharge or to produce particles during the plasmageneration.

Further, since the particles in the region above the wafer effectivelymask the parts to be processed on the wafer to thereby reduce the yield,it is required that these particles have to be purged out of the regionabove the wafer especially while the plasma is being generated. Inaddition, by suppressing the yield reduction, the productivity isexpected to improve.

SUMMARY OF THE INVENTION

It is a first object of the present invention to provide a plasmaprocessing apparatus and method for inhibiting the attachment of theparticles to prevent the contamination of the wafer.

It is a second object of the present invention to provide a plasmaprocessing apparatus and method for removing the particles from theregion above the wafer during the plasma generation to enhance theproductivity.

In accordance with one aspect of the present invention, there isprovided a plasma processing apparatus comprising a plasma generatingunit for generating a plasma in a processing chamber in which a setprocessing is performed on a substrate serving as an object to beprocessed, the plasma processing apparatus further comprising a particlemoving unit for electrostatically driving particles in a region abovethe substrate to thereby be removed out of the region above thesubstrate in the processing chamber while the processing on thesubstrate is performed by using the plasma.

Preferably, the particle moving unit includes: a mounting table formounting the substrate; a first electrode for electrostaticallyadsorbing the substrate onto the mounting table; a ring-shaped memberinstalled to enclose a periphery of the substrate; a second electrodefor electrostatically adsorbing the ring-shaped member onto the mountingtable; a first power supply, connected to the first electrode, forsupplying an electric power with a first electric potential; and asecond power supply, connected to the second electrode, for supplying anelectric power with a second electric potential different from the firstelectric potential, wherein the mounting table, the first electrode, thering-shaped member, and the second electrode are installed in theprocessing chamber.

Preferably, the particle moving unit includes a voltage controller forcontrolling at least a potential of the second electrode to remove theparticles from the region above the substrate to a region above thesecond electrode.

Preferably, the second electric potential is higher than the firstelectric potential when the particles are negatively charged during theplasma processing.

Preferably, the first electric potential is of negative polarity and thesecond electric potential is of positive or negative polarity.

Preferably, the second electric potential is higher than an electricpotential formed near a surface of the substrate in the region above thesubstrate in response to the first electric potential or a self-biaspotential formed by the generation of the plasma.

Preferably, the plasma processing apparatus further comprises a particleremoving unit for removing the particles in the processing chamber.

Preferably, the plasma processing apparatus further comprises anexhausting unit for exhausting the processing chamber.

In accordance with another aspect of the present invention, there isprovided a plasma processing method of a plasma processing apparatus,comprising the steps of generating a plasma in a processing chamber inwhich a set processing is performed on a substrate serving as an objectto be processed; and performing the processing on the substrate by theplasma, the plasma processing method further comprising the step ofelectrostatically driving particles in a region above the substrate tothereby be removed out of the region above the substrate in theprocessing chamber during the processing on the substrate.

Preferably, the plasma processing apparatus includes a mounting tablefor mounting the substrate; a first electrode for electrostaticallyadsorbing the substrate onto the mounting table; a ring-shaped memberinstalled to enclose a periphery of the substrate; a second electrodefor electrostatically adsorbing the ring-shaped member onto the mountingtable; a first power supply, connected to the first electrode, forsupplying an electric power with a first electric potential; and asecond power supply, connected to the second electrode, for supplying anelectric power with a second electric potential different from the firstelectric potential, wherein the mounting table, the first electrode, thering-shaped member, and the second electrode are installed in theprocessing chamber, and wherein the step of driving particles includesthe substep of supplying the electric power with a second electricpotential different from the first electric potential to the secondelectrode by the second power supply.

Preferably, the step of driving particles further includes the substepof controlling at least a potential of the second electrode to removethe particles from the region above the substrate to a region above thesecond electrode.

Preferably, the second electric potential is higher than the firstelectric potential when the particles are negatively charged during theplasma processing.

Preferably, the first electric potential is of negative polarity and thesecond electric potential is of positive polarity.

Preferably, the first electric potential is of negative polarity and thesecond electric potential is of negative polarity.

Preferably, the second electric potential is higher than an electricpotential formed near a surface of the substrate in the region above thesubstrate in response to the first electric potential or a self-biaspotential formed by the generation of the plasma.

Preferably, the plasma processing method further comprises the step ofremoving the particles in the processing chamber.

Preferably, the plasma processing method further comprises the step ofexhausting the processing chamber.

In accordance with the present invention, since the particles in theregion above the substrate are electrostatically driven out of theregion above the substrate in the processing chamber during theprocessing on the substrate by the plasma, the attachment of theparticles can be inhibited, thereby preventing the contamination of thewafer. Further, the particles are removed from the region above thesubstrate during the plasma generation, thereby enhancing theproductivity.

Still further, the second power supply supplies the electric power witha second electric potential different from the first electric potentialto the second electrode for electrostatically adsorbing the ring-shapedmember installed at the periphery of the substrate onto the mountingtable, thereby efficiently inhibiting the attachment of the particles.

Still further, at least a potential of the second electrode iscontrolled to remove the particles from the region above the substrateto a region above the second electrode, thereby efficiently inhibitingthe attachment of the particles.

Still further, the second electric potential is higher than the firstelectric potential when the particles are negatively charged during theplasma processing, thereby efficiently inhibiting the attachment of theparticles.

Still further, the first electric potential is of negative polarity andthe second electric potential is of positive polarity, therebyefficiently inhibiting the attachment of the particles.

Still further, the second electric potential is higher than an electricpotential formed near a surface of the substrate in the region above thesubstrate in response to the first electric potential or a self-biaspotential formed by the generation of the plasma, thereby efficientlyinhibiting the attachment of the particles.

Still further, the particles are removed in the processing chamber,thereby efficiently inhibiting the attachment of the particles.

Still further, the processing chamber is exhausted, thereby efficientlyinhibiting the attachment of the particles.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodiments,given in conjunction with the accompanying drawings, in which:

FIG. 1 shows a cross sectional view schematically illustrating aconfiguration of a plasma processing apparatus in accordance with apreferred embodiment of the present invention;

FIG. 2 provides a graph representing a relation between an electricpower for generating a plasma and the number of particles;

FIG. 3 describes an electric potential distribution formed in theprocessing chamber 100 shown in FIG. 1;

FIG. 4 exemplarily illustrates particle trajectories in a plasma regionunder a potential distribution represented by equipotential lines inFIG. 3;

FIG. 5A exemplarily depicts particle trajectories observed from anobservation system shown in FIG. 7; and FIG. 5B is a partial enlargedview of FIG. 5A;

FIG. 6 presents a graph showing a relation between the number of theparticles observed as in FIGS. 5A and 5B and a voltage applied to an ESCelectrode 122 a for FR adsorption;

FIG. 7 schematically shows a configuration of the observation system forobserving the particles to obtain the experimental results described inFIGS. 5A, 5B and 6; and

FIG. 8 schematically illustrates a configuration of the conventionalplasma processing apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a preferred embodiment of the present invention will bedescribed with reference to the drawings.

FIG. 1 shows a cross sectional view schematically illustrating aconfiguration of a plasma processing apparatus in accordance with apreferred embodiment of the present invention.

A plasma processing apparatus shown in FIG. 1 includes a processingchamber 100 which is a cylindrical container for a prearrangedplasma-using processing (hereinafter, referred to as “plasmaprocessing”), e.g., an etching, a sputtering or a CVD (chemical vapordeposition), to be performed on a semiconductor wafer (hereinafter,referred to as “wafer”) functioning as an object to be processed; and isconfigured as, for example, a parallel-plate type CCP (capacitivelycoupled plasma) processing apparatus.

The processing chamber 100 includes a chamber sidewall 110, an upperelectrode 111 installed at the top of the chamber, a lower electrode 112installed in a lower portion of the processing chamber 100, an ESC(electrostatic chuck) stage 120 (mounting table) mounted on an upperside of the lower electrode 112, and an annular shaped baffle plate 130interposed between the chamber sidewall 110 and the lower electrode 112.

In addition, to the outside of the processing chamber 100 is connected agas exhaust line made of a tube-shaped member, and pumps such as a turbomolecular pump TMP and a dry pump DP are installed in the gas exhaustline. The pumps evacuate the processing chamber 100 via the baffle plate130, exhausting gas containing particles by using a waste gas scrubber.Further, these pumps can be installed in the chamber sidewall 110 notvia the baffle plate 130 but via a valve that can be freely opened andclosed.

The upper electrode 111, which has a plurality of through holes notshown in the drawing, serves as a shower head for introducing a processgas for the plasma processing into the processing chamber 100 throughthe through holes. The lower electrode 112 is connected to a highfrequency power supply 113 for providing a high frequency (RF: radiofrequency) power.

The ESC stage 120 includes a focus ring (FR) 121 mounted on an upperside thereof; a wafer-adsorbing ESC electrode 120 a (first electrode)embedded in the ESC stage 120 for electrostatically adsorbing themounted wafer onto the ESC stage 120; and an FR-adsorbing ESC electrode122 a (second electrode) embedded in the ESC stage 120 forelectrostatically adsorbing the focus ring 121 onto the ESC stage 120.The focus ring 121 is made of a ring-shaped member formed to enclose thewafer mounted on the upper side of the ESC stage 120.

The FR-adsorbing ESC electrode 122 a is connected via an LPF (low passfilter) to an FR-adsorbing variable power supply 122 (second powersupply) for providing a power required to adsorb the focus ring 121 ontothe FR-adsorbing ESC electrode 122 a. The wafer-adsorbing ESC electrode120 a is connected via an LPF (low pass filter) to a variable powersupply 125 (first power supply) for providing a power required to adsorbthe wafer onto the FR-adsorbing ESC electrode 122 a. These LPFs arenecessary because the ESC electrodes 120 a and 122 a are provided withan RF power generated by a capacitive coupling between the RF powersupplied to the lower electrode 112 and the RF power supplied to the ESCelectrode 120 a and 122 a through an insulted region in the ESC stage120. The variable power supplies 122 and 125 are connected to a voltagecontrol unit, which will be described later.

The plasma processing apparatus performs a plasma processing such as anetching on an oxide film already formed on an upper side of the wafer byusing, for example, a plasma generated under an intermediate vacuumlevel. To generate the plasma, a high frequency (RF) electric field isgenerated in a space between the upper electrode 111 and the lowerelectrode 112 by providing an RF power to the lower electrode 112. (Aplasma generating unit.) The plasma thus generated forms a plasma regionin the processing chamber 100 as shown in FIG. 1.

The particles detached from places such as an inner wall on the chambersidewall and the like float around in the processing chamber 100,especially in the plasma region thereof. The particles, floating in theplasma region, attract electrons contained in the plasma to therebybecome negatively charged.

As shown in FIG. 1, a bulk plasma region, which is a central portion ofthe plasma region, has a positive polarity relative to a referencevoltage 0 V of the upper electrode 111 and a substantially constant highelectric potential (voltage). On the contrary, an ion sheath region (IonSheath, Dark Space), which is formed near the wafer surface in a regionabove the wafer, forms a large potential gradient due to the influenceof an electrostatic force of the lower electrode 112 and the electricpotential of the bulk plasma region. Thus, the electric potential of theion sheath region is lower than the bulk plasma region, and the polaritythereof is negative. Further, a potential gradient is formed in a plasmaperiphery region, i.e., the plasma region excluding the bulk plasmaregion.

Therefore, the particles negatively charged by attracting the electronsin the plasma tend to float around in an upper part of the ion sheathregion (the region above the wafer) within the plasma periphery region,because of a balance between the gravity pulling down the particlesvertically and the upwardly repelling force generated by a potentialgradient formed over a range from the negatively polarized ion sheathregion to the positively polarized plasma periphery region, i.e., apotential difference between the surface of the lower electrode 112 andthe bulk plasma region as well as an attractive force toward thepositively polarized bulk plasma region.

FIG. 2 provides a graph representing a relation between a plasma powerfor generating plasma and the number of particles.

In FIG. 2, “plasma power” of the horizontal axis represents powerconsumption [W] calculated from the voltage and current applied to thehigh frequency power supply 113 for generating the plasma; and “numberof particles” of the vertical axis represents the number of theparticles observed in the processing chamber 100 when different voltagesare applied to the high frequency power supply 113, i.e., the number ofthe particles detached from the chamber sidewall 110.

As shown in FIG. 2, the number of the particles decreases as the plasmapower increases. This is because the electrostatic force of thegenerated plasma gets stronger as the plasma power gets higher so thatthe particles are efficiently exhausted from the region above the wafer.Therefore, it is preferable that the voltage applied to the highfrequency power supply 113 for generating the plasma is high and theplasma power ranges from 100 W to 4000 W.

FIG. 3 describes an electric potential distribution formed in theprocessing chamber 100 shown in FIG. 1.

As shown in FIG. 3, in the plasma processing apparatus, an electricpotential distribution represented by the electric force lines, i.e.,dotted lines and the equipotential lines, i.e., solid lines is formed inthe processing chamber 100 when electric powers of different voltagesare applied to the ESC electrodes 120 a and 122 a, respectively.Further, the electric force lines represent the case where the electricpotential of the power applied to the wafer-adsorbing ESC electrode 120a (first potential) is lower than that applied to the focus ring 121(second potential).

Further, the turn-on and turn-off of the power is controlled by thevoltage control unit (sequential control unit) shown in FIG. 1 asfollows.

In case of turning on the power, the voltage control unit turns on thepower to the wafer-adsorbing ESC electrode 120 a after the RF power forgenerating the plasma is turned on, e.g., after 1 second therefrom; andthen, turns on the power to the FR-adsorbing ESC electrode 122 a after apredetermined time within a range of, for example, 0 to 100 msec. (Thevoltage control unit.) Further, in case of turning off the power, thevoltage control unit turns off the power to the FR-adsorbing ESCelectrode 122 a; subsequently turns off the power to the wafer-adsorbingESC electrode 120 a after a predetermined time within a range of, forexample, 0 to 100 msec; and then, turns off the RF power after, e.g., 1second therefrom. Thus, the potential distribution shown in FIG. 3 canbe formed in the processing chamber 100 while the atmosphere in theprocessing chamber 100 is electrostatically stable, but not while theatmosphere in the processing chamber 100 is electrostatically unstable,namely, right after the plasma is generated or the plasma isextinguished.

The voltage control unit has been described to control the turn-on andturn-off of the power application to the wafer-adsorbing ESC electrode120 a. However, the voltage control unit may well be able to control thevoltage of the power to be applied to the FR-adsorbing ESC electrode 122a while it monitors the power application to the wafer-adsorbing ESCelectrode 120 a.

As shown in the equipotential lines described above, during the plasmaprocessing, the focus ring 121 and the wafer is electrostaticallyadsorbed respectively onto high-voltage parts and low-voltage parts ofthe ESC stage 120. Further, the particles negatively charged byattracting the electrons contained in the plasma are also attractedunder the influence of the electrostatic force towards high-voltageregions.

FIG. 4 exemplarily illustrates particle trajectories in a plasma regionin case of such potential distribution represented by equipotentiallines shown in FIG. 3. Further, FIG. 5A exemplarily depicts particletrajectories observed from an observation system that will be describedin FIG. 7, and FIG. 5B is a partial enlarged view thereof.

As depicted by the particle trajectories in the plasma region (theregion above the wafer) in FIGS. 4, 5A and 5B, when the potentialdistribution represented by the equipotential lines as shown in FIG. 3is formed, the particles floating in the plasma region are driven out ofthe region above the wafer to somewhere above the focus ring 121 underthe influence of the electrostatic force to be attracted towards thehigh-voltage region. (A particle moving unit.) To remove the particlesefficiently, the potential of the FR-adsorbing ESC electrode 122 a ispreferably higher than the potential of the wafer-adsorbing ESCelectrode 120 a; and more preferably, higher than the potential formedin response thereto near the upper side of the wafer or the self-biaspotential formed by the plasma generation.

Further, as shown in FIGS. 5A and 5B, the particle trajectories near thewafer are closely spaced in the horizontal direction, and those abovethe focus ring 121 are spread widely in the horizontal direction. Thisshows that the particles are accelerated from a place above the wafer toanother place above the focus ring. This is because the particles getaccelerated by being repelled by the potential difference between theself-bias potential of the ion sheath region and the potential of theplasma periphery region, i.e., the region between the surface of thelower electrode 112 and the bulk plasma region and, at the same time,attracted by a high potential of the FR-adsorbing ESC electrode 122 a.

Furthermore, preferably, the potential of the FR-adsorbing ESC electrode122 a is of polarity opposite to that of the self-bias potential in caseof setting the ground as a reference voltage 0 V or the potential formednear the upper side of the wafer in response to the potential of thewafer-adsorbing ESC electrode 120 a in case of setting the ground as areference voltage 0 V; in other words, of positive polarity. Thus, thepotential of the FR-adsorbing ESC electrode 122 a can easily be madehigher than the self-bias potential or the potential formed near theupper side of the wafer in response to the potential of thewafer-adsorbing ESC electrode 120 a, thereby a force attracting theparticles onto somewhere above the focus ring 121 can be ensured to begenerated.

FIG. 6 presents a graph showing a relation between the number of theparticles observed as in FIGS. 5A and 5B and a voltage applied to an ESCelectrode 122 a for FR adsorption. Further, FIG. 6 exemplifies ameasurement result of the number of the particles observed by theobservation system 600 shown in FIG. 7, which will be described later.

In FIG. 6, “voltage applied to focus ring” of the horizontal axisrepresents the voltage applied to the FR-adsorbing ESC electrode 122 ain case where the voltage applied to the wafer-adsorbing ESC electrode120 a (hereinafter, referred to as “voltage applied to the wafer”) isconstant at 0 V that is the reference voltage of the ground. Therefore,the voltage applied to the focus ring also represents a relativepotential difference with respect to the voltage applied to the wafer(hereinafter, referred to as “relative potential difference”).

As shown in FIG. 6, if the voltage applied to the focus ring is higherthan the voltage applied to the wafer (for example, the voltage appliedto the focus ring is +200 V, i.e., the relative potential difference is+200 V), the number of the particles over the wafer is small but thenumber of the particles over the focus ring 121 is large. On thecontrary, if the voltage applied to the focus ring is not higher thanthe voltage applied to the wafer (for example, the voltage applied tothe focus ring is 0 V, −120V, or −150 V, i.e., the relative potentialdifference is 0 V, −120V, or −150 V), the number of the particles overthe wafer is large but the number of the particles over the focus ring121 is small.

Further, as shown in FIG. 6, the number of the particles over the waferdecreases and that over the focus ring 121 increases as the relativepotential difference increases. Preferably, if the relative potentialdifference is +150 V or higher, the number of the particles over thewafer can certainly be made smaller than that over the focus ring 121.

Referring to FIGS. 3 to 6, by setting the potential of the powersupplied to the wafer-adsorbing ESC electrode 120 a lower than thepotential of the power supplied to the FR-adsorbing ESC electrode 122 a,the number of the particles in the region above the wafer during theplasma processing, especially the number of the particles in the plasmaperiphery region and the ion sheath region, i.e., the particles insomewhere between the bulk plasma region and the wafer surface, isreduced, thereby the attachment of the particles can be suppressed tothereby prevent the wafer contamination.

Further, since the particles in the region above the wafer during theplasma processing are driven out of the region above the wafer, theeffect described hereinafter can be achieved.

By reducing the particles effectively masking the portion to beprocessed on the wafer, the plasma processing can be carried out withoutbeing obstructed by the particles, thereby the yield can be increasedand thus the productivity can be enhanced.

Since the number of particles over the wafer can be reduced during theplasma processing, a cleaning operation of the processing chamberperformed before the plasma processing can be facilitated; and, morespecifically, the cleaning cycle can be extended, the seasoning timeafter a wet cleaning can be shortened, and, further, the start-up timeof the plasma processing apparatus can be shortened. As a result, theoperation time of the plasma processing apparatus can be increased,thereby significantly enhancing the productivity.

FIG. 7 schematically shows a configuration of the observation system forobserving the particles to obtain the experimental results described inFIGS. 5A, 5B and 6.

In FIG. 7, the observation system 600 includes a laser light source 610,which is of SHG-YAG laser, for applying a laser beam with a wavelengthof 532 nm onto the particles in the processing chamber 100, and animage-enhancement type CCD camera 620 for imaging the inside of theprocessing chamber 100. Furthermore, in the observation system 600, ahalf-wave plate 611, lenses 612 and 613, slits 614 and 615, and a lightextinction device 616 are arranged in this order along the light pathfrom the laser light source 610 to apply laser light scattering method.Between the slits 614 and 615 is inserted the processing chamber 100(see FIG. 4). A beam of light, scattered by the particles in theprocessing chamber 100, enters the CCD camera 620 via an interferencefilter 621 used for the light with a wavelength of 532 nm.

In the plasma processing apparatus shown in FIG. 1, if the plasma isextinguished by stopping the power application to the ESC electrodes 120a and 122 a after completing the plasma processing, the particles in theprocessing chamber 100 are removed because the plasma chamber 100 isexhausted via the baffle plate 130 by the exhaust pumps. (A particleremoving unit, an exhausting unit.) Further, the exhausting process canbe carried out during the plasma processing.

Since the exhaust pumps evacuate via the baffle plate 130 in the lowerportion of the processing chamber 100, the exhausting efficiency isgenerally low in the region near the wafer surface. However, asdescribed with reference to FIGS. 3 to 6, the particle removingefficiency of the exhaust pumps can be enhanced because the particlesare moved to a region where the exhausting efficiency of the pump ishigh, i.e., towards a region above the focus ring 121 near the baffleplate 130, during the plasma processing. Therefore, we can make it surethat the particles are prevented from being attached onto the uppersurface of the wafer after the plasma extinction.

In the plasma processing apparatus in accordance with the preferredembodiment, the plasma to be generated was exemplified as a CCPgenerated by an RF power. However, other kinds of plasma such as an ICP(inductive coupled plasma) generated by an RF power or a UHF (ultrahighfrequency plasma) generated by a microwave can also be used therein.

The plasma processing apparatus in accordance with the preferredembodiment of the present invention can be applied to plasma-usedprocesses such as an etching process, a sputtering process, and a CVDprocess.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

1. A plasma processing apparatus comprising a plasma generating unit forgenerating a plasma in a processing chamber in which a set processing isperformed on a substrate serving as an object to be processed, theplasma processing apparatus further comprising a particle moving unitfor electrostatically driving particles in a region above the substrateto be removed out of the region above the substrate in the processingchamber while the processing on the substrate is performed by using theplasma.
 2. The plasma processing apparatus of claim 1, wherein theparticle moving unit includes: a mounting table for mounting thesubstrate; a first electrode for electrostatically adsorbing thesubstrate onto the mounting table; a ring-shaped member installed toenclose a periphery of the substrate; a second electrode forelectrostatically adsorbing the ring-shaped member onto the mountingtable; a first power supply, connected to the first electrode, forsupplying an electric power with a first electric potential; and asecond power supply, connected to the second electrode, for supplying anelectric power with a second electric potential different from the firstelectric potential, wherein the mounting table, the first electrode, thering-shaped member, and the second electrode are installed in theprocessing chamber.
 3. The plasma processing apparatus of claim 2,wherein the particle moving unit includes a voltage controller forcontrolling at least an electric potential of the second electrode toremove the particles from the region above the substrate to a regionabove the second electrode.
 4. The plasma processing apparatus of claim2, wherein the second electric potential is higher than the firstelectric potential when the particles are negatively charged during theplasma processing.
 5. The plasma processing apparatus of claim 2,wherein the first electric potential is of negative polarity and thesecond electric potential is of positive polarity.
 6. The plasmaprocessing apparatus of claim 2, wherein the first electric potential isof negative polarity and the second electric potential is of negativepolarity.
 7. The plasma processing apparatus of claim 2, wherein thesecond electric potential is higher than an electric potential formednear a surface of the substrate in the region above the substrate inresponse to the first electric potential or a self-bias potential formedby the generation of the plasma.
 8. The plasma processing apparatus ofclaim 1, further comprising a particle removing unit for removing theparticles in the processing chamber.
 9. The plasma processing apparatusof claim 8, further comprising an exhausting unit for exhausting theprocessing chamber.
 10. A plasma processing method of a plasmaprocessing apparatus, comprising the steps of generating a plasma in aprocessing chamber in which a set processing is performed on a substrateserving as an object to be processed; and performing the processing onthe substrate by the plasma, the plasma processing method furthercomprising the step of electrostatically driving particles in a regionabove the substrate to be removed out of the region above the substratein the processing chamber during the processing on the substrate. 11.The plasma processing method of claim 10, wherein the plasma processingapparatus includes a mounting table for mounting the substrate; a firstelectrode for electrostatically adsorbing the substrate onto themounting table; a ring-shaped member installed to enclose a periphery ofthe substrate; a second electrode for electrostatically adsorbing thering-shaped member onto the mounting table; a first power supply,connected to the first electrode, for supplying an electric power with afirst electric potential; and a second power supply, connected to thesecond electrode, for supplying an electric power with a second electricpotential different from the first electric potential, wherein themounting table, the first electrode, the ring-shaped member, and thesecond electrode are installed in the processing chamber, and whereinthe step of driving particles includes the substep of supplying theelectric power with a second electric potential different from the firstelectric potential to the second electrode by the second power supply.12. The plasma processing method of claim 11, wherein the step ofdriving particles further includes the substep of controlling at leastan electric potential of the second electrode to remove the particlesfrom the region above the substrate to a region above the secondelectrode.
 13. The plasma processing method of claim 11, wherein thesecond electric potential is higher than the first electric potentialwhen the particles are negatively charged during the plasma processing.14. The plasma processing method of claim 11, wherein the first electricpotential is of negative polarity and the second electric potential isof positive polarity.
 15. The plasma processing method of claim 11,wherein the first electric potential is of negative polarity and thesecond electric potential is of negative polarity.
 16. The plasmaprocessing method of claim 11, wherein the second electric potential ishigher than an electric potential formed near a surface of the substratein the region above the substrate in response to the first electricpotential or a self-bias potential formed by the generation of theplasma.
 17. The plasma processing method of claim 10, further comprisingthe step of removing the particles in the processing chamber.
 18. Theplasma processing method of claim 17, further comprising the step ofexhausting the processing chamber.